Abstract:
The present study was carried out to investigate the spatial variation of physico - chemical parameters and
sediment characteristics in some areas of the Jaffna estuary in order to assess the differences among sites
with respect to the measured parameters. A total of 29 stratified samplings were made on a fortnightly
basis from October 2013 to April 2014. Surface water samples were collected along the selected GPS 12
Channel and physico-chemical parameters and bottom characteristics were also measured. Estuary depths
increased significantly (p<0.05) from 40 to 770 cm at Nagathevanthurai, Pooneryn and Mandaitivu I
respectively though water temperature was not significantly different. Salinity values were significantly
(p<0.05) different with a wide range having 60 ppt at Chavakachcheri while it was 32 ppt in Mandaitivu
IV. Water pH was alkaline at most of the sampling sites. Minimum value of electrical conductivity was
recorded in Mandaitivu I as 15.56 mS/cm and the electrical conductivity value at Ketpali was 29.50 mS/
cm. The turbidity range was between 12.64 – 48.50 g/L with the lowest values at Velanai I (Allaipitty)
and significantly (p<0.05) higher values were recorded at Kachchai. The dissolved oxygen concentration
measured at Velanai III (Chettypullam) was significantly (p<0.05) high (12.47 mg/L) and the lowest value
was recorded at Pooneryn II (Poovarasamtheevu), which was 7.00 mg/L. Percentage of organic matter in
the Kakkaitheevu I (Madaaruku) and Mandaitivu I ranged between 1.04 and 6.80 respectively. Percentage
of silt – mud was followed by sand were the prominent sediment features in the Jaffna estuary. Results
of the present study emphasize the spatial heterogeneity of physico-chemical and bottom characteristics
in the Jaffna estuary.
